As illustrated in FIGS. 1 and 2A–2C, rotating signs 30 are well known in the advertising industry. More particularly, rotating billboards typically include a plurality of rotating column members 32. These column members 32 typically have a triangular shape so that they may be positioned adjacent one another and simultaneously rotated without interference from one another. More particularly, the column members 32 may be moved between first, second and third positions. FIG. 2A illustrates a column member 32 positioned in a first position, according to the prior art. FIG. 2B illustrates a column member 32 being moved between the first position, as illustrated in FIG. 2A, and a second position, as illustrated in FIG. 2C. The triangular shape of the column members 32 allows for three different advertisements to be positioned on a single billboard.
U.S. Pat. No. 3,921,321 to Weisskopf discloses a sign including a plurality of rotatable column members. More specifically, the rotatable column members have a triangular shape, and each of the column members are rotated in a circular path. Accordingly, a plurality of triangularly shaped column members may be positioned adjacent one another and still rotate in a circular path without interfering with one another. Each of the triangularly shaped column members are connected to a chain drive assembly. Movement of the chain drive assembly causes rotation of the triangularly shaped column members. Accordingly, up to three different signs, or advertisements, may be displayed on the sign.
Accordingly, a rotating billboard having triangularly shaped column members may advantageously allow simultaneous rotation of the column members while positioned adjacent one another. Of course, increasing the number of advertisements carried by a billboard may advantageously increase advertising revenue. Unfortunately, however, billboards having triangularly shaped column members are limited to displaying three advertisements. To increase the number of advertisements displayed on the billboard may require the use of a plurality of four-sided column members. Four-sided column members, however, positioned adjacent one another could not rotate in a circular path without substantial interference.
In an attempt to solve this problem, U.S. Pat. No. 1,650,205 to Grower et al. discloses a billboard system having a plurality of four-sided column members that are spaced-apart and separated by structural frame member. Each of the column members have a plurality of panels, and the column members may be individually rotated. More specifically, one panel may be displaced in a predetermined direction to decrease the size of the column member so that an adjacent column member may rotate. In other words, one of the sides of the four-sided column member may be inwardly displaced to make room for an adjacent column member to rotate.
Another attempt to provide a display system having a rotatable four-sided column is disclosed in U.S. Pat. No. 1,362,542 to Rogers. Each column member includes four display members, and a pair of opposing curved guided walls for aligning the display members on each column member as they are rotated to a display position. The curved guide walls also act to initially pivot each display member approximately 60 degrees to allow the column member to rotate from a first display position to a second display position. This type of display system, however, is limited to displaying only two different displays.
Yet another attempt to provide a display system having a plurality of four-sided column members is disclosed in U.S. Pat. No. 1,112,921 to La Pearl. The four-sided column members in the La Pearl '921 patent are spaced-apart to facilitate rotation along a substantially circular path without interference with one another. More specifically, the sign includes a plurality of leafs to fill in the spaces between the rotating column members to provide the appearance of a continuous front display face.
There exist several different types of drive assemblies to rotate column members of a display system. For example, the Weisskopf '321 patent, discussed above, discloses a chain drive assembly to rotate column members. U.S. Pat. No. 5,572,816 to Anderson, Jr. et al. discloses a rotating sign having a cylindrical shape and a plurality of elongate louvers that rotate as the sign rotates. Rotation of each of the louvers may be accomplished using a chain drive assembly.
Another type of drive assembly for rotating an object is disclosed in U.S. Pat. No. 4,521,983 to Wakatake. More specifically, the drive assembly is a magnetic motor mechanism to rotate a sign 90 and/or 180-degrees. The magnetic motor includes four poles having an arcuate shape to allow for 90 and/or 180-degree rotation of the object.